Pollution-free incineration system

ABSTRACT

An incinerator has a first combustion chamber which receives the waste to be incinerated. An ignition-burner is provided in the first chamber to ignite the waste; the burner automatically turns off at waste incineration temperature. Burning of the refuse is accomplished in three zones, each zone being provided with proper temperature and a supply of regulated air at low velocity by means of natural aspiration, controlled by thermal feedback wherein the changing of the refuse fire changes the heat and vacuum applied to a conduit and orifice system of fire air injection resulting in automatic combustion control. A second combustion chamber is spaced above and communicates with the first chamber. Separators are provided in each chamber for separating partially burned particles from the fully burned combustion gases and preventing the particles from rising beyond the respective separators. An after-burner is arranged to project a substantially horizontal flame into the second combustion chamber; the flame produced by the after-burner substantially filling the cylindrical second chamber and reducing any microscopic particles or unburned gases which have passed through the separators. The second chamber passes fully reduced combustion gas to the stack at a temperature of 2,000* Fahrenheit.

United States Patent [191 Vanderveer [4 1 May 7,1974

[ POLLUTION-FREE INCINERATION SYSTEM 221 Filed: Aug. 7, 1972 [21] Appl. No.: 278,632

[52] US. Cl. 110/8 C, 100/8 A, 110/119 [51] Int. Cl. F23g 5/12 [58] Field of Search 110/8 R, 8 A, 8 C, 18 R,

' ll0/18 C, 119

[5 6] References Cited UNITED STATES PATENTS 3,645,218 2/1972 Davis ll0/8 3,043,248 7/1962 Martin 110/8 3,560,165 2/1971 Beasley 1l 0/8 3,310,009 3/1967 Jacobs 110/8 3,489,109 l/1970 Flowers, Jr. 110/119 3,495,555 2/1970 Boyd et al ll0/8 3,552,332 l/l971 Mattenley 110/19 Primary Examiner-Kenneth W. Sprague Attorney, Agent, or Firm-Friedman & Goodman receives the waste to be incinerated. An ignitionburner is provided in the first chamber to ignite the waste; the burner automatically turns off at waste incineration temperature.

Burning of the refuse is accomplished in three zones, each zone being provided with proper temperature and a supply of regulated air at low velocity by means of natural aspiration, controlled by thermal feedback wherein the changing of the refuse fire changes the heat and vacuum applied to a conduit and orifice system of fire air injection resulting in automatic combustion control. A second combustion chamber is spaced above and communicates with the first chamber. Separators are provided in each chamber for separating partially burned particles from the fully burned combustion gases and preventing the particles from rising beyond the respective separators. An after-burner is arranged to project a substantially horizontal flame into the second combustion chamber; the flame produced by the after-bumer substantially filling the cylindrical second chamber and reducing any microscopic particles or unburned gases which have passed through the separators. The second chamber passes fully reduced combustion gas to the stack at a temperature of 2,000 Fahrenheit.

31 Claims, 13 Drawing Figures PATENIED HAY 71974 SHEET 1 [1F 7 Pmammw 11w 3.808.619

SHEET 3 UP 7 J 7////// //ZA Fess Irv?

FIGA.

PATENIED MAY 7 i374 SHEET 5 OF 7 FI G.8

PATENTED W 7 SHEET 7 or 7 FIGIB.

POLLUTION-FREE INCINERATION SYSTEM BACKGROUND OF THE INVENTION The present invention relates to incineration systems, and more particularly to an incineration system for the burning of waste materials without the production of smoke, fumes,'particles, fly-ash or odors Specifically, the invention is for an incineration system which includes two incineration chambers with separating means in each for preventing the further rise of substantial parts of the pollutants produced during incineration into the stack and subsequent discharge into the atmosphere. All unburned products of combustion pass through a substantially horizontal flame projected into the second chamber by an after-burner the afterburner flame totally reducing gases and the particles of combustion from the lower chamber.

Incinerators for burning refuse and the like are already known. According ,to one type of incinerator, a main incinerating chamber is provided in which the refuse is received and burned. A second after-burner chamber is provided substantially above the first chamber or main chamber and communicates therewith. The products of combustion, i.e., the particles of combustion which have not been fully reduced, are directed into the after-burner chamber where after-burner flames are provided to reduce the upwardly moving particles. This system, as well as other incinerator systems, has made use of blowers which inject air into at least one of the incinerating chambers. While air is required for burning the refuse, thisair injection has had the disadvantageous effect of forcing the gases, together with the products of combustion, to be driven upwardly at a fairly rapid rate. To permit the high rate of egress of air from the combustion chambers, the flow paths for the rising gases have usually been left unobstructed. The disadvantage of these systems is that the rapid rates at which airis blown into the chambers and at which the gases leave the chambers result in a substantial amount of polluting particles, i.e., the gases and products of combustion, leaving the combustion chamber before being fully reduced. This prior type of incinerator system has substantially contributed to air pollution. 7 I

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an incinerating system which does not have the disadvantages known in prior incinerator systems.

Another object of the present invention is to provide an incinerator system of the type under discussion which is simple in construction and economical to manufacture and operate.

Still another object of the present invention is to provide an incinerator system as above described which incinerates waste materials and the like while fully reducing the products of combustion to harmless, sterile gases normally occuring in the atmosphere. These are carbon dioxide, water vapor and air, all superheated to 2,000 and sterilized.

Still another object of the. present invention is to provide an incinerator system which totally eliminates the polluting by -produc-ts which are normally given off by similar types of incinerator systems.

It is a further object of the present invention to provide an incinerator system which burns waste material as well as the polluting combustion products formed thereby at a plurality of ascending levels the larger particles of combustion being prevented from continued ascension with the hot rising combustion gases in at least one of the levels.

A still further object of the present invention is to provide an incinerator system having an after-burner chamber which communicates with a stack, which chamber intercepts gaseous or microscopic particles of combustion these particles of combustion so intercepted being reduced by a substantially horizontally projected flame generated by an after-burner, the

- flame projecting across and fully filling the after-burner chamber in a reverberant manner, projecting outward and then back towards the inlet by sweeping around the rim causing any unreduced smoke, gas or microscopic particle matter to be fully burned by the churning action of the transverse and reverberant after-burner flame.

According to the present invention, an incinerator for burning waste material and for eliminating both small and large particles and incompletely combusted gaseous vapors or malodorous substances formed by the combustion thereof, comprises a substantial hollow housing and means having a first combustion chamber adapted to receive thewaste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber. Air supply means are provided for supplying a regulated stream of air into said first combustion chamber. Ignition-burner means are arranged to project the flame in the direction of waste material in said first combustion chamber to thereby initially ignite the waste material, the ignition burner then being turned off by a temperature-sensing switch when waste material combustion has become self-sustaining. First and second particle separating and reducing means are respectively provided in said first and second combustion chambers for separating the large particles from the microscopic particles and gases and for deflecting the large particles and preventing a substantial portion thereof from rising above the respective separating means. After-burner means are provided and arranged to project a flame into said second combustion chamher for fully reducing the gas products or microscopic particles which have risen above said second separating means in said second combustion chamber. Stack means are provided which communicate with said second chamber means for removing the particle-free hot air and hot, clean gas from the latter.

According to the presently preferred embodiment, said second chamber comprises a substantially cylindrical vertical wall with open bottom and top ends, said top end communicating with said stack means while said bottom-end is positioned directly above said second particle separating means. Transverse partition means are provided mounted below said bottom-end, said second particle separating means being mounted on said partition means. Said second chamber means incorporates screen means for the purpose of momentarily constraining refuse driven rapidly upwards past the first and second particle separating means as a result of an explosion of aerosol cans in the incinerator. The screen means extends substantially transversely across the cross-section of said second chamber for preventing the passage of the refuse particles beyond said second chamber into said stack means. According to an advantageous feature of the present invention, said screen means comprises a shear screen having a periphery which is closely spaced to said vertical wall to form an annular space between said shear and said lateral wall, and said screen means is placed vertically at such height that the after-burner flame skims across the screen with a shearing of action, consuming the refuse and keeping the screen clear of build up.

With the construction of the incinerator, as broadly described above, the waste material or the like is burned and any unburned products of combustion are effectively separated for reburning prior to entering a final after-burner chamber in which they are fully reduced to gaseous carbon dioxide and super heated water vapor at a temperature of 2,000 Fahrenheit being rendered thereby fully sterile and inocuous.

While the present invention contemplates the addition of or supply of air into the respective combustion chambers, the present invention does not include the use of forced air means as often used in prior art incinerators. The air flow as well as the flow of the hot gases in the present incinerator naturally rise by the process of convection after the air and the gases have been heated by the burning refuse. Instead of accelerating the ascent of rising gases, the particle separating means have the reverse effect. Advantageously, theair flames which are projected by the two burner means are projected in substantially horizontal directions instead of in upward directions as taught by some of the prior art this also having the effect of slowing down the rate of ascent of the rising gases. The rate of supply of air into the combustion chambers is regulated by a thermal feed back conduit and orifice system with locked proportioning control dampers so that the temperature as well as the rate of ascent can closely be regulated. By regulating the rate of ascent of the rising gases as well as of the polluting particles and effectively slowing this rate, the particles are more fully combusted. Also, by deflecting a substantial portion of the larger particles back into the first chamber, only the smallest particles can reach the second chamber these easily being fully reduced by the after-burner means.

BRIEF DESCRIPTION OF THE DRAWINGS With the above and additional objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 is a vertical cross-section of an incinerator in accordance with the present invention;

FIG. 2 is a cross-section of the incinerator shown in FIG. 1, taken on line A-A;

FIG. 3 is a cross-section of the incinerator shown in FIG. 1, taken on line BB;

FIG. 4 shows cross-sections of the incinerator shown in FIG. 1, taken on lines C--C and DD;

FIG. 5 is across-section of the incinerator shown in FIG. 1, taken on line E-E;

FIG. 6 is a perspective view of a portion of a particulate reburner utilized in the incinerator shown in FIG.

FIG. 7 shows two particulate reburners similar to that shown in FIG. 6, showing typical directions of gas and particulate streams and the separating and reburning action of the particulate reburners when used in the incinerator;

FIG. 8 is a cross-section of the incinerator as shown in FIG. 1, taken on line F-F;

FIG. 9 is a section of the incinerator taken on line YY in FIG. 8;

FIG. 10 is a cross-section of the incinerator as shown in FIG. 1, taken on line G-G;

FIG. 11 is a perspective view of the shear screen an supporting structure which is shown to partially extend into the after-burner chamber shown in FIG. 12;

FIG. 12 shows the details of the upper portion of the incinerator shown in FIG. 1 as well as showing the flow directions of hot gases thereabout, the after-burner chamber being shown partly in cross-section; and

FIG. 13 is a cross-section of the upper portion shown in FIG. 12, taken along the line Z-Z, showing the manner in which the reverberant flame fills the upper portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The incinerator 10, as shown in FIG. 1, consists of a main body housing 12 having a lower incinerating portion 14 and an upper stack portion 13. The lower incinerating portion 14 is utilized to combust the waste material, as will be described hereafter, while the upper stack portion 13 serves to carry away the heated pollution-free gases. The lower incinerating portion 14 is provided with a first combustion chamber 15 which serves as the refuse compartment. The first combustion chamber 15 is accessible from the outside by a door 16 which may be pivotally mounted and locked in a known manner. In the lower region of the door 16, there is provided a loading chute 17. A grate 18 extends from the region of the loading chute 17 and is inclined downwardly in a direction away from the loading chute. The grate is configurated to carry or support refuse l9 and may comprise a plurality of parallel iron bars forming a frame, in a well-known manner. The grate 18 is supported by a plurality of grate support beams 20 which may have an H cross-section. However, support beams having any other cross-section may equally well be used.

Associated with the combustion chamber 15 are three zones where combustion takes place. The zones are not exactly demarcated from one another, but may slightly overlap. Zone 1 generally defines that area beneath the stack of refuse 19 which is initially ignited by brief operation of an optional ignition burner 22. The ignition burner 22 is arranged to project a substantially horizontal flame in the direction of the grate 18 the flame coming into contact with the bottom of the refuse stack 19 to ignite the same. The ignition burner 22 is turned on when the incinerator is started and is turned off automatically when the refuse pile is burning properly at adequate temperature. After the ignition burner is turned off, heating and drying of refuse stack 19 occurs due to the action of convected and radiant heat from above.

A heated refuse receptacle 24 is positioned directly beneath the grate 18. The heated refuse receptacle is trough-shaped and closed on each end. It is configurated to capture radiant and impinging heat from the burning refuse and from the ignition burner 22 during the time when the burner is on. Any refuse residue that falls into the receptacle is further reduced to a finewhite powder under the influence of heat both from the burner 22 and the burning refuse 19. Accumulation of unburned drippings, ash or refuse is completely avoided due to the refuse receptacle temperature of l,400 Fahrenheit.

The main body housing 12 has a bottom wall 26 lined with sectional refractories 27, as are the other walls of the incinerator. The refractories serve to confine the flame within the incinerator while protecting the metal parts and retain the heat generated therein in a wellknown manner. The bottom wall 26 is provided with an under-fire air inlet 28. The air inlet 28 is arranged to permit ambient air to flow into the chamber 15. The air drawn in through the air inlet 28 is drawn in by natural convection flow due to-the rising gases in the chamber and the vacuum induced by the stack. At least one air inlet 28 is to be provided, although more than one air inlet is preferable in order to more uniformly distribute the incoming air throughout the chamber 15. As can be readily seen in FIG. 2, three air inlets 28 are provided in the preferred embodiment which are substantially equally spaced from each other and extend across the width of the incinerator. The air which passes through the air inlets 28 will be referred to as under-fire air and is preheated by forcing it to flow around the heated refuse receptacle 24 which contains the burned-out residual ash. This arrangement assures that efficient operation is obtained since the heat below the grate 18 would otherwise be wasted. ,The rising columns of under-fire air provides the warm, dry air under the refuse pile l9 necessary to effectively burn the refuse. The underfire air is used to burn the refuse in zone 1 this air being utilized both to burn the refuse 19 when the ignition burner 22 is caused to project a flame towards the refuse and to maintain the refuse burning subsequent to ignition.

Heating and drying of refuse occurs in zone 1 under the action of the ignition burner, as well as by convected and radiated heat. Combustion of unburned particles occurs in zone 2 as a result of mixing with air which is supplied from a zone burning automatic supplementalair regulator'34, to be more fully described below. Similarly, gas burning occurs in zone 3 athigh temperatures subsequent to mixing with air from the zone burning automatic supplemental air regulator. The fuel rich gases are burned when the heated air from the zone burning automatic supplemental air regulator 34 turbulently mix with the air starved fuel-rich gases of zone 3 at the zone 3 burning ports or air outlets 38. Thus, the refuse is primarily dried and preheated to combustion temperature in zone 1, and the heated supplemental air, with fresh supplies of oxygen, released in zone 2 makes it possible to sustain the burning of the refuse pile 19 with the proper proportion of air. Burning of gases and carbon monoxide occurs in zone 3 at temperatures of.2,700 Fahrenheit when preheated air turbulently mixes with the evolved gases.

The zone burning automatic supplemental air regulator referred to above, forming an important feature of the present invention, has a zone burning air inlet 30 through which ambient air containing oxygen can flow, as generally designated by the arrows 32. The zone burning automatic supplemental air regulator 34 generally comprise air conduits 34' which are elongated and proportional to the flame temperature and the size of the fire in the chamber 15. As the refuse fire increases, more air is needed. This need is met by the increase in availability of warm air convected upwards after being heated by the heat of the fire. In addition, the larger the refuse fire, the stronger the draft and internal vacuum of the incinerator is, this draft or vacuum drawing more heated air through the air conduits 34. The proportioning control damper 36 sets the level or proportion of supplemental air according to the draft which is also a function of the location of the incinerator and stack height. Once the proportion of air (between underfire air and zone burning supplemental air) is determined, the proportioning control damper is locked and no further adjustment is ever needed as the air conduits 34 maintain the proper air for zones 2 and 3 fully automatically in accordance with the varying temperature and draft vacuum. Three of the walls of the chamber 15 are provided with ports or outlets 38 which communicate the interiors of the air conduits 34 with the interior of the chamber 15. The air-drawn in through the inlet 30 flows past the control damper 36 and is heated while passing through the conduit 34. The air then passes through the respective outlets 38, emptying into zones 2 and 3. The direction of the heated air-flow which emanates from the conduits 34 is generally designated by the reference numeral 40.

In the upper region of the chamber 15, there are provided a plurality of particulate reburners 42. Four transverse reburners are shown in FIG. 1, each of the reburners being spaced closely to one another at a distance corresponding to approximately twice the largest particle dimension. The specific construction of the reburners 42 will be more specifically described hereafter in connection with FIGS. 6 and 7. It should be pointed out here, however, that the particulate reburners essentially function as particle separators, i.e., each particulate reburner obstructs the passage of the rising hot gasestogether with the uncombusted polluting particles therein and is effective for deflecting the large particles back into the chamber. 15 while permitting only the smaller particles and burned gases to pass between two adjacent reburners 42. Intermediate size particles are held in troughs of the reburners until they are burned out.

A fence or partition means 46 is provided above the particulate reburners 42. The fence will be more specifically described with reference to FIG. 11. However, it is here pointed out that the fence 46 substantially extends transversely across the chamber 15 and blocks a substantial part of the hot rising gases from ascending at increased velocities. One of the primary functions of the fence 46 is to block the hot rising gases and force them into turbulance after they have passed the particulate reburners 42. Another function of the fence 46 is to force all the rising gases past a turbulator strip 47 into a confined passage 54, as to be more fully described hereafter. Positioned on the top surface of the transverse portion of the fence 46 are a plurality of flow eddy traps 48. The hot rising gases which have passed through the passage 54 are directed across the flow eddy traps 48 where their state of turbulance causes any particles to become entrapped therein and held until burned down.

An upwardly extending screen support member 50 is mounted on the fence 46 along the general axis of symmetry of the incinerator chamber 15. A shear screen 52 is mounted on the screen support number 50 the shear screen 52 being positioned in an after-burner chamber 56. The after-burner chamber 56 has a substantially cylindrical vertical wall 57 and open upper and lower ends. An after-burner 58 cooperates with an opening in the vertical wall 57 of the after-burner chamber 56 and is arranged to project a substantially horizontal flame which skims the upper surface of the shear screen 52 and burns explosion-produced particles there entrapped, as will further be described hereafter. The upper open end of the after-burner chamber 56 communicates with the upper stack portion 13.

The upper stack portion 13 comprises a stack 60 and a draft regulator 62. The draft regulator comprises a plate with a weight, adjustable to conditions inside and outside the chambers to maintain an appropriate draft, and thereby maintain the proper vacuum inside the incinerator. The construction of the draft regulator 62 is well known and does not form a part of the present invention.

FIG. 3 illustrates the general construction of the grate 18. As mentioned above, the grate is supported by grate support I-I-bar beams inclined at an angle downwards from the door 16. The grate can be mounted so that it can be simply pulled forward for cleaning for allowing unburnable material to drop into the refuse receptacle 24. A cleanout door 25, as can be seen in FIGS. 1 and 2, is provided on the side of the heated refuse receptacle 24. The receptacle 24 can be slid out of the lower incinerating portion 14 for emptying the refuse receptacle. FIG. 3 also illustrates six air conduits 34 disposed about three sides of the incinerator 10. The number of air conduits 34 provided is not critical to the present invention and any suitable number may be used. Also shown in FIG. 3 are the proportioning control regulators 36 mounted in each of the air conduits 34. A portion of the grate 18 has been cut away in FIG. 3 to illustrate the position of the flame projecting portion of the ignition burner 22 this portion being positioned below the grate l8 and arranged to project flames in a substantially horizontal direction.

FIG. 4 represents cross-sections taken at zones 2 and 3 both of these cross-sections being identical. This view illustrates the general configuration of the combustion chamber 15 and shows the zone burning air outlets or ports 38 which communicate the interiors of the air conduits 34 and of the chamber 15. Also shown in FIG. 4 is the loading door 16 through which the refuse 19 is passed onto loading chute 17 and into the chamber 15. The interior of the chamber 15 is substantially lined with sectional refractories 27 which serve to contain the flames.

The sectional view shown in FIG. 5 illustrates the particulate reburners 42, the latter forming another important feature of the present invention. Each particulate reburner 42 comprises an elongated member which extends across the width of the incinerator 10 and is supported at each end in the walls of the incinerator 10 in any suitable manner. The particulate reburners are mounted transversely across the refuse compartment 15, below the horizontal portion of the fence 46. Each reburner 42 functions to separate small and large particles rising with the heated gases. More particularly, the function of the particulate reburners is to separate the particles which have not been fully combusted. The unburned matter or particles have different dimensions and weights ranging from very small to larger particles. The specific gravity of the fully burned gases is much lighter than that of the unburned particles. Referring to FIG. 6, the particulate reburners 42 substantially have a Y-cross-section and include a vertical deflector 70. The vertical deflector traps all transverse components of gas flow. Each vertical deflector is substantially flat and elongated and has extending from the top thereof two sidewardly and upwardly extending particle separators 72. Downwardly extending eddy current lips 74 are provided at the top ends of the particle separators 72. The two particle separators 72 together form a reburner trough 7 6. The particulate reburner 42 is shown to be made from two bent sections and can be joined at the vertical deflector portions 70 in any suitable manner. However, any other construction which is suitable may be used. For example, the particulate reburner 42 may be formed from one elongated sheet which is configurated to have two vertical deflectors 70 and two particle separators 72 the reburner being formed by bending the point at which the vertical deflectors 70 are joined to one another. Referring to FIG. 7, the reburner troughs 76 are adapted to receive and contain fine particles 80 which are to be reduced. Typical directions of gas and particulate streams are designated by the reference numerals 82 in FIG. 7. The streams are generally upwardly directed and in directions towards the vertical deflectors 70. The particulate reburners 42 are so configurated that the vertical deflectors 70 trap all transverse components of flow and substantially the flow is abruptly turned about outwards in a concave manner wherein the action of the centrifugal force generated spins the heavier particles of matter outwardly and across and then downwardly. The downwardly moving particles generally the heavier and larger particles are trapped under the eddy current lips 74 of the respective particulate reburners. Only the generally clear-hot gases still containing some smaller and lighter particles can usually pass through the space formed between adjacent particulate reburners 42 and be permitted to continue the upward flow towards the after-burner chamber 56. The paths of the lighter particles are generally designated by the reference numeral 84, while the paths of the heavier particles are generally designated by the reference numeral 86.

The upper surfaces of the reburners 42 are hollow and incorporate trough-shapes, as described above. The small outer lips 74 of the reburners 42 serve to create eddy currents on the top surfaces of the particle separators 72. This turbulance sweeps fine or light particles that may have passed through the openings between adjacent particle separators 72 into the back edge and into the region of the rarified pressure occuring over the trough section 76. The particles fall into the trough 76 where they are exposed to high temperatures. The light particles 80 are exposed to high temperatures and are slowly roasted, in a state of incandescence, into a fully reduced gaseous state. The particle reburners 42 are mounted so that they can be turned over and emptied for cleaning.

The construction of the flow eddy traps 48 as well as of the fence 46 are more fully illustrated in FIGS. 8 and 9. The fence 46 generally comprises a horizontal fence portion 46a somewhat concave (on the lower surface) and a vertical fence portion or sheet 46b, angled upwards in the direction of the gas passage 54. The fence 46 controls the flame and the gas flow in the area above the particulate reburners 42 and maintains a high temperature in the troughs 76 of the particulate reburners 42. The fence 46 incorporates a substantially vertical fence portion 46b which, together with the walls of the lower incinerator portion as well as of the after-burner chamber 56, forms substantially annular passages which communicate the interiors of the chambers and 56. Built into the fence 46 and integral therewith are flow eddy traps 48 which create a suction vortex for all transverse elements of flow. The general design of the passages in the upper portion of the main body housing 12 is such that all flow must have transverse elements to reach the opening at the bottom of the afterburner chamber 56. The after-burner chamber 56 has an axis of symmetry and the trapping chambers or flow eddy traps 48 comprise an array formed by a plurality of radial walls 48a passing through the axis and a plurali ty of chordal walls 48b each extending between two adjacent radial walls 48a. The chordal walls 48b are substantially equally spaced from each other in the radial direction of the axis. All parts of the traps are advantageously made of thin, heat-resistant metal strips arranged on edge. Arranged at the top of the vertical fence portion 48b is a turbulator strip 47. The turbulator strip 47 is arranged at an angle to the vertical fence portion 46b. The tubular strip creates a zone of high turbulance to all flow of gases in the passage 54 before entering the transverse flow area of the flow eddy traps 48.

The detailed construction of the after-burner region of the incinerator is shown in FIGS. l0, l2 and 13. The

horizontal fence portion 46a has mounted thereon the flow eddy traps 48. The screen support member 50 generally consists of a screen support 50a which is mounted on four radially extending legs 50b which are angularly equally spaced from one another. Extending downwardly from each leg 50b is a post 50c the length of the posts 500 differing from one another and being so selected so that the screen supports 50:; is generally mounted in a vertical direction despite the fact that it is mounted on the sloped horizontal fence portion 46a. The screen support member 50 construction can also be seen in FIG. 11 this FIGURE also showing the specific configuration of the shear screen 52. At the periphery of the shear screen 52, there is provided a downwardly bent portion 52a, as can best be seen in FIG. 11. The diameter of the shear screen 52 is so selected so that an annular space is formed between the periphery of the shear screen 52A and the cylindrical vertical wall 57 of the after-burner chamber 56. The lengths of the posts 500, as well as of the screen support stem 50a, are so selected so that the screen 52 is positioned inside the after-burner chamber 56. The shear screen 52 is positioned generally at the level of the after-burner 58 input opening in the after-burner wall 57.

The after-burner chamber 56 is so positioned, so that all gases from the refuse compartment 15 flows through it. Any uncombusted smoke or particle matter is burned fully by churning action of the transverse and reverberant flame 108 of the after-burner 58. The flame 108, Section Z-Z shown in FIGS. 12 and 13, is reverberant across the cylindrical after-chamber 56, travelling outward and back towards the inlet while sweeping around the rim of periphery of the afterburner wall 57. The position of the shear screen is located just below the lower edge of the after-burner flame 108 so that the flame which eminates from the after-burner 58 skims the upper surface of the screen 52 and keeps it clean by means of a shearing action.

The operation of the incinerator will now be described. To incinerate refuse or waste material or the like, the door 16 is opened and the material to be burned is thrown into the chamber 15 therethrough. Once the refuse is on the grate l8, burning of the refuse may be initiated by a brief operation of the ignition burner 22. The ignition burner 22 may be shut off by known temperature detection or control means as soon as the flame is self-sustaining. Alternatively, the ignition burner 22 may be continuously, intermittently or manually operated. However, it has been found that most efficient and pollution-free operation may be obtained by shutting off the ignition burner 22 after the refuse 19 has been ignited and the fire is self-sustainin g. As the refuse l9 burns, the air above the refuse is heated by the flames 90 and rises naturally by convection. The drop in pressure in the lower chamber causes under-fire air to be drawn in through the air inlets 28 the air passing around the heated refuse receptacle 24 and becoming heated thereby. By the time the air passing through the inlets 28 reaches the refuse 19, the air has beenheated and dried and is suitable for burning of the refuse. The refuse 19, however, does not fully combust during burning on the grates 18 and some of the remaining particles are drawn up with the heated gases above the refuse l9 pile the particles, forming the basis of smoke and pollution, rise with the rising gases past zones 2 and 3. Because a great deal of the oxygen present in the air entering through the inlets 28 is utilized for burning the refuse 19, there would normally be little oxygen for continued combustion of the rising particles or pollutants. Consequently, oxygen rich air which has been preheated during passage in the air conduits 34 is provided and generally is designated by the reference numeral 40. The heat in the chamber 15 as well as the incandescent nature of the rising particles, cause the incoming air 40 to further combust the rising particles and gases the further combustion generally being designated by the flames 94 in the regions of the outlets or ports 38. Burning in the three zones is generally controlled by the configuration of the various air passages, the draft regulation, thermal conductivity and convection, and the initial callibration of the system may be made by the suitable adjustment of the proportioning control dampers 36 which are locked at the satisfactory position and are not subsequently moved. The particles which have not been fully reduced above zone 3 continue to rise with the rising hot and finer particles continue to rise upwardly through the passage 54 into the region of the after-burner chamber 56. This flow is generally designated by arrows 98 and 100 in FIG. 12. The gases flow past the tubulator strip 47 and across the eddy traps 48 as shown by arrows 102 and 104 these traps again separating the larger particles and trappings the same while permitting the microscopic particles to further rise with the rising gases. Larger particles which have been driven upward by exploding aerosol cans are intercepted by the shear screen 52. The particles are trapped by the screen and prevented to a great extent from further rising towards the stack 60. The afterburner 58, continuously on during incinerator operation, projects a flame substantially in a horizontal direction in the region of the shear screen 52 which skims the upper surface of the screen and keeps it clean by totally reducing the particles contained on the screen. The gases 112 which leaves the upper end of the afterburner chamber 56 essentially comprises clear hot air and gases which are free of any uncombusted particles which impart color or odor thereto, and are fully sterilized and inocuous.

Thermal balance and air flow to and through the three zones are automatically maintained as incineration conditions and temperatures vary. Particles, smoke, fumes and odor emissions are controlled fully by the net effect of the cumulative results of the operation of the above described features. It should be noted, however, that the incinerator operation is based on the upward flow of gases as a result of convection due to heating no forced air being blown through the incinerator. As a result, the rising gases, as well as the pollutants are not forcibly driven upwards and remain in the incinerator for longer periods of time to thereby permit the pollutants to be more fully combusted or reduced. The construction is selected to retard the rise of the gases and particles in the incinerator rather than to permit the gases to accellerate and to leave the burner chambers at higher velocities.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of the invention which is for purposes-of illustration only and is not to be construed as a limitation of the invention.

What is claimed is:

1. An incinerator for burning waste material and for eliminating particles and for fully combusting gas formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber; air supply means for providing a stream of air into said first combustion chamber to permit an upward flow by induction of gas and particles of combustion through said housing means; deflecting particle separating means in one of said combustion chambers provided with spaces having dimensions greater than those of the particles of combustion for separating large particles from small particles when combustion of waste material is taking place by substantially downwardly deflecting the large particles back into said first combustion chamber for reburning and preventing a substantial portion thereof from rising above said separating means while permitting the small particles to pass through said spaces and be deposited on a top surface of said separating means in a state of incandescence until fully reduced to gas, whereby said particle separating means does not become clogged by the particles of combustion; and after-burner means arranged above said particle separating means for projecting a substantially horizontal and reverberant flame into said second combustion chamber substantially transversely to the direction of upward flow of gas and particles of combustion to create great heat and turbulence therein and for fully reducing any microscopic particles or unburned gases which have risen into said second combustion chamber above said separating means.

2. An incinerator as defined in claim 1, further comprising another particle separating means in the other of said combustion chambers for separating the small particles from the large particles and deflecting the small particles from the large particles and preventing a substantial portion thereof from rising above said other particle separating means.

3. An incinerator as defined in claim 1, further comprising receptacle means arranged in the lower region of said first chamber for receiving heated refuse and ash which is generated by the burning of the waste material.

4. An incinerator as defined in claim 3, wherein said first chamber has a bottom wall positioned directly beneath said receptacle means, said air supply means comprising air inlet in said bottom wall which communicates the outside of said first chamber with the interior wall thereof for receiving air, whereby the air which passes through said air inlet comes into contact with said receptacle to thereby become heated by the heated refuse and rise by convection and pass the region where the waste material is being burned.

5. An incinerator as defined in claim 1, wherein said second chamber comprises a substantially cylindrical vertical wall with open bottom and top ends said top end being adapted to release rising gases during combustion, and said bottom end communicating with said first chamber.

6. An incinerator as defined in claim 5, wherein said vertical wall has an opening, and wherein said afterburner means is connected to said vertical wall and arranged to project a flame into said second chamber through said opening to substantially fill said entire second chamber.

7. An incinerator as defined in claim 6, wherein said after-burner means is arranged to project said flame in a substantially horizontal direction, whereby said vertical wall directs the flame to return towards said opening.

8. An incinerator for burning waste material and for eliminating particles formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber; air supply means for providing a stream of air into said first combustion chamber, said air supply means comprising at least one substantially upwardly directed conduit extending along said first combustion chamber, in heat transmissive relationship therewith, said first chamber having at least one outlet opening which communicates the interiors of said conduit and said first chamber and having an inlet opening in the region of its lower end, whereby heat generated in said first chamber heats the air in said conduit and causes the same to move by convection from said inlet opening into the interior of said first chamber through said outlet opening, this movement of air further being induced by internal incinerator vacuum; at least one particle separating means provided in one of said combustion chambers for separating large particles from small particles when combustion of waste material is taking place and deflecting the large particles back into said first combustion chamber and preventing a substantial portion thereof from rising above said one separating means; and after-burner means arranged to project a substantially horizontal and reverberant flame into said second combustion chamber for creating great heat and turbulence therein and for fully reducing the particles which have risen into said second combustion chamber above said one separating means.

9. An incinerator as defined in claim 8, wherein said first chamber has a vertical wall, and wherein a plurality of conduits are spaced about at least a portion of said vertical wall.

10. An incinerator as defined in claim 8, further including a proportioning control regulator arranged in said conduit for regulating the quantity of air which is permitted to flow through saidconduit.

11. An incinerator for burning waste material and for eliminating particles formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber; support means arranged in said first chamber for supporting the waste material therein, said support means comprising a grate extending substantially across the entire cross section of said first chamber; a plurality of transversely extending H- beams in said first chamber which support said grate; air supply means for providing a stream of air into said first combustion chamber; at least one particle separating means provided in one of said combustion chambers for separating large particles for small particles when combustion of waste material is taking place and deflecting the large particles and preventing a substantial portion thereof from rising above said one separating means; and after-burner means arranged to project a substantially horizontal and reverberant flame into said second combustion chamber for creating great heat andturbulence therein and for fully reducing microscopic particles which have risen into said second combustion chamber above said one separating means.

12. An incinerator for burning waste material and for eliminating particles formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber; air supply means for providing a stream of air into said first combustion chamber; at least one particle separating means provided in one of-said combustion chambers for separating large particles from small particles when combustion of waste material is taking place and deflecting the large particles and preventing a substantial portion thereof from rising above said one separating means,

.said one separating means being located in said first chamber and comprising at least one transversely extending elongated deflector having a Y shaped cross section; and after-burner means arranged to project a substantially horizontal and reverberant flame into said second combustion chamber for creating great heat and turbulence therein and for fully reducing microscopic particles which have risen into said second combustion chamber above said one separating means.

13. An incinerator as defined in claim 12, wherein each deflector has a first portion which is flat and elongated and which extends substantially downwardly, and has a second portion extending to each side of said first portion sidewardly and upwardly from the top of said first portion, and wherein a plurality of deflectors and provided closely spaced from each other so that spaces remain between adjacent second portions, said second portions being arranged to deflect the large particles, while said spaces are arranged to pass the small particles in an upward direction with rising hot air, and restrain said small particle for rebuming.

14. An incinerator as defined in claim.12, further comprising partition means arranged in said first chamber for preventing rising air from passing directly into said second chamber over the major cross-section of said first chamber.

15. An incinerator as defined in claim 14, said partition means comprises a fence wall configurate d to have a transverse portion and an upward portion, said transverse portion being arranged to block the rising air from further upward movement while directing the air toward said upward portion, the latter portion forming with the wall of said first chamber a passage which communicates said first and second chambers. 16. An incinerator as defined in claim 15, wherein said upward portion is provided at the top thereof with a transverse turbulator strip which is adapted to deflect and turbulate the air as it passes from the regions of said first to said second chambers.

17. An incinerator for burning waste material and for eliminating particles formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber, said second chamber comprising a substantially cylindrical vertical wall with open bottom and top ends, said top end being adapted to release rising gases during combustion, and said bottom end communicating with said first chamber; transverse partition means having a top surface and mounted between said bottom end; air supply means for providing a stream of air into said first combustion chamber; one particle separating means provided in said first chamber for separating large particles from small particles when combustion of waste material is taking place and deflecting the large particles and preventing a substantial portion thereof from rising above said separating means; an other particle separating means mounted on said partition means to at least partially extend into said second chamber through said bottom end; and after-burner means arranged to project a substantially horizontal and reverberant flame into said second combustion chamber for creating great heat and turbulence therein and for fully reducing microscopic particles which have risen into said second combustion chamber above said one separating means.

18. An incinerator as defined in claim 17, wherein said other particle separating means comprises a plurality of trapping chambers having open top ends, said trapping chambersbeing arranged on said top surface and arranged in the flow path of the rising air from said first to said second chambers, whereby the air passing over the trapping chambers causes the air to turbulate and the particles entering the trapping chambers remain therein until reduced to gas by roasting.

19. An incinerator as defined in claim 18, wherein said second chamber has an axis of symmetry and wherein said trapping chambers comprise an array formed by a plurality of radial walls passing through said axis and a plurality of chordal walls each extending between two adjacent radial walls, said chordal walls being substantially equally spaced from each other in the radial direction of said axis. I

20. An incinerator as defined in claim 17, further comprising constraining means in the form of screen means extending transversely substantially across the entire cross-section of said second chamber for preventing the passage of the explosion-driven material from being transmitted beyond said second chamber until reduced to gas by burning.

21. An incinerator as defined in claim 20, wherein said vertical wall has an opening, said screen means being mounted on said partition means in the region of said opening, and said after-burner means being arranged to project a flame into said second chamber through said opening, wherein said flame substantially surrounds said screen and reduces particles which have deposited thereon.

22. An incinerator as defined in claim 21, wherein said screen means comprises a shear screen having a periphery which is closely spaced to said lateral wall to form an annular space between said shear screen and said lateral wall.

23. An incinerator as defined in claim 22, wherein said periphery of said shear screen is sloped downwardly and positioned just below said opening so that a flame generated by said after-burner means skirts a surface defined by said shear screen.

24. An incinerator as defined in claim 1, further comprising ignition-burner means arranged to project a flame in the direction of the waste material in said first combustion chamber to thereby ignite the waste material.

25. An incinerator as defined in claim 1, wherein said particle separating means comprises a plurality of parallel elongate transversely extending deflectors, the

27. An incinerator as defined in claim 1, wherein said spaces provided in said separating means are substan tially greater than average-sized particles which rise from said first to said second chambers.

28. An incinerator as defined in claim 6, wherein said after-burner means is positioned exteriorly of said second chamber and is arranged to project a reverberant flame into said chamber, whereby the temperatures within said second chamber can be raised to a desired high level without damaging said after-burner means.

29. An incinerator as defined in claim 1, further comprising support means in the form of a grate arranged in the lower region of said first chamber for supporting the waste material; receptacle means in the form of an ash pan arranged below said grate for receiving partially burned refuse and also ash generated by the burning of the waste material and for receiving wet waste and drippings thereof; and further ignition burner means arranged to project a flame in the direction of the waste material on said grate to ignite the same and which flame further sweeps across said receptacle means to reduce the waste material which drops thereinto.

30. An incinerator as defined in claim 29, wherein said first chamber has a bottom wall positioned below said receptacle means, said air inlet means comprising air inlet openings in said bottom wall, whereby air which passes through said air inlet openings comes into direct contact with said receptacle means to cool the same and maintain the temperature of said receptacle means below the melting point of the latter.

31. An incinerator as defined in claim 29, wherein said grate is inclined downwardly in the direction away from said further ignition burner means, with the highest point of said grate being above and further ignition burner means, whereby the flame of said further ignition burner means flame sweeps across substantially the entire under surface of said grate and is downwardly directed into said receptacle means by the converging action of said inclined grate. 

1. An incinerator for burning waste material and for eliminating particles and for fully combusting gas formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber; air supply means for providing a stream of air into said first combustion chamber to permit an upward flow by induction of gas and particles of combustion through said housing means; deflecting particle separating means in one of said combustion chambers provided with spaces having dimensions greater than those of the particles of combustion for separating large particles from small particles when combustion of waste material is taking place by substantially downwardly deflecting the large particles back into said first combustion chamber for reburning and preventing a substantial portion thereof from rising above said separating means while permitting the small particles to pass through said spaces and be deposited on a top surface of said separating means in a state of incandescence until fully reduced to gas, whereby said particle separating means does not become clogged by the particles of combustion; and after-burner means arranged above said particle separating means for projecting a substantially horizontal and reverberant flame into said second combustion chamber substantially transversely to the direction of upward flow of gas and particles of combustion to create great heat and turbulence therein and for fully reducing any microscopic particles or unburned gases which have risen into said second combustion chamber above said separating means.
 2. An incinerator as defined in claim 1, further comprising another particle separating means in the other of said combustion chambers for separating the small particles from the large particles and deflecting the small particles from the large particles and preventing a substantial portion thereof from rising above said other particle separating means.
 3. An incinerator as defined in claim 1, further comprising receptacle means arranged in the lower region of said first chamber for receiving heated refuse and ash which is generated by the burning of the waste material.
 4. An incinerator as defined in claim 3, wherein said first chamber has a bottom wall positioned directly beneath said receptacle means, said air supply means comprising air inlet in said bottom wall which communicates the outside of said first chamber with the interior wall thereof for receiving air, whereby the air which passes through said air inlet comes into contact with said receptacle to thereby become heated by the heated refuse and rise by convection and pass the region where the waste material is being burned.
 5. An incinerator as defined in claim 1, wherein said second chamber comprises a substantially cylindrical vertical wall with open bottom and top ends said top end being adapted to release rising gases during combustion, and said bottom end communicating with said first chamber.
 6. An incinerator as defined in claim 5, wherein said vertical wall has an opening, and wherein said after-burner means is connected to said vertical wall and arranged to project a flame into said second chamber through said opening to substantially fill said entire second chamber.
 7. An incinerator as defined in claim 6, wherein said after-burner means is arranged to project said flame in a substantially horizontal direction, whereby said vertical wall directs the flame to return towards said opening.
 8. An incinerator for burning waste material and for eliminating particles formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber; air supply means for providing a stream of air into said first combustion chamber, said air supply means comprising at least one substantially upwardly directed conduit extending along said first combustion chamber, in heat transmissive relationship therewith, said first chamber having at least one outlet opening which communicates the interiors of said conduit and said first chamber and having an inlet opening in the region of its lower end, whereby heat generated in said first chamber heats the air in said conduit and causes the same to move by convection from said inlet opening into the interior of said first chamber through said outlet opening, this movement of air further being induced by internal incinerator vacuum; at least one particle separating means provided in one of said combustion chambers for separating large particles fRom small particles when combustion of waste material is taking place and deflecting the large particles back into said first combustion chamber and preventing a substantial portion thereof from rising above said one separating means; and after-burner means arranged to project a substantially horizontal and reverberant flame into said second combustion chamber for creating great heat and turbulence therein and for fully reducing the particles which have risen into said second combustion chamber above said one separating means.
 9. An incinerator as defined in claim 8, wherein said first chamber has a vertical wall, and wherein a plurality of conduits are spaced about at least a portion of said vertical wall.
 10. An incinerator as defined in claim 8, further including a proportioning control regulator arranged in said conduit for regulating the quantity of air which is permitted to flow through said conduit.
 11. An incinerator for burning waste material and for eliminating particles formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber; support means arranged in said first chamber for supporting the waste material therein, said support means comprising a grate extending substantially across the entire cross section of said first chamber; a plurality of transversely extending H-beams in said first chamber which support said grate; air supply means for providing a stream of air into said first combustion chamber; at least one particle separating means provided in one of said combustion chambers for separating large particles for small particles when combustion of waste material is taking place and deflecting the large particles and preventing a substantial portion thereof from rising above said one separating means; and after-burner means arranged to project a substantially horizontal and reverberant flame into said second combustion chamber for creating great heat and turbulence therein and for fully reducing microscopic particles which have risen into said second combustion chamber above said one separating means.
 12. An incinerator for burning waste material and for eliminating particles formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber; air supply means for providing a stream of air into said first combustion chamber; at least one particle separating means provided in one of said combustion chambers for separating large particles from small particles when combustion of waste material is taking place and deflecting the large particles and preventing a substantial portion thereof from rising above said one separating means, said one separating means being located in said first chamber and comprising at least one transversely extending elongated deflector having a Y-shaped cross section; and after-burner means arranged to project a substantially horizontal and reverberant flame into said second combustion chamber for creating great heat and turbulence therein and for fully reducing microscopic particles which have risen into said second combustion chamber above said one separating means.
 13. An incinerator as defined in claim 12, wherein each deflector has a first portion which is flat and elongated and which extends substantially downwardly, and has a second portion extending to each side of said first portion sidewardly and upwardly from the top of said first portion, and wherein a plurality of deflectors and provided closely spaced from each other so that spaces remain between adjacent second portions, said second portions being arranged to deflect the large particles, while said spaces are arranged to pass the small particles in an Upward direction with rising hot air, and restrain said small particle for reburning.
 14. An incinerator as defined in claim 12, further comprising partition means arranged in said first chamber for preventing rising air from passing directly into said second chamber over the major cross-section of said first chamber.
 15. An incinerator as defined in claim 14, said partition means comprises a fence wall configurated to have a transverse portion and an upward portion, said transverse portion being arranged to block the rising air from further upward movement while directing the air toward said upward portion, the latter portion forming with the wall of said first chamber a passage which communicates said first and second chambers.
 16. An incinerator as defined in claim 15, wherein said upward portion is provided at the top thereof with a transverse turbulator strip which is adapted to deflect and turbulate the air as it passes from the regions of said first to said second chambers.
 17. An incinerator for burning waste material and for eliminating particles formed by the combustion thereof, comprising substantially hollow housing means having a first combustion chamber adapted to receive the waste material and a second combustion chamber spaced substantially above and communicating with said first combustion chamber, said second chamber comprising a substantially cylindrical vertical wall with open bottom and top ends, said top end being adapted to release rising gases during combustion, and said bottom end communicating with said first chamber; transverse partition means having a top surface and mounted between said bottom end; air supply means for providing a stream of air into said first combustion chamber; one particle separating means provided in said first chamber for separating large particles from small particles when combustion of waste material is taking place and deflecting the large particles and preventing a substantial portion thereof from rising above said separating means; an other particle separating means mounted on said partition means to at least partially extend into said second chamber through said bottom end; and after-burner means arranged to project a substantially horizontal and reverberant flame into said second combustion chamber for creating great heat and turbulence therein and for fully reducing microscopic particles which have risen into said second combustion chamber above said one separating means.
 18. An incinerator as defined in claim 17, wherein said other particle separating means comprises a plurality of trapping chambers having open top ends, said trapping chambers being arranged on said top surface and arranged in the flow path of the rising air from said first to said second chambers, whereby the air passing over the trapping chambers causes the air to turbulate and the particles entering the trapping chambers remain therein until reduced to gas by roasting.
 19. An incinerator as defined in claim 18, wherein said second chamber has an axis of symmetry and wherein said trapping chambers comprise an array formed by a plurality of radial walls passing through said axis and a plurality of chordal walls each extending between two adjacent radial walls, said chordal walls being substantially equally spaced from each other in the radial direction of said axis.
 20. An incinerator as defined in claim 17, further comprising constraining means in the form of screen means extending transversely substantially across the entire cross-section of said second chamber for preventing the passage of the explosion-driven material from being transmitted beyond said second chamber until reduced to gas by burning.
 21. An incinerator as defined in claim 20, wherein said vertical wall has an opening, said screen means being mounted on said partition means in the region of said opening, and said after-burner means being arranged to project a flame into said second chamber through said opening, wherein said flame substantially surrounds sAid screen and reduces particles which have deposited thereon.
 22. An incinerator as defined in claim 21, wherein said screen means comprises a shear screen having a periphery which is closely spaced to said lateral wall to form an annular space between said shear screen and said lateral wall.
 23. An incinerator as defined in claim 22, wherein said periphery of said shear screen is sloped downwardly and positioned just below said opening so that a flame generated by said after-burner means skirts a surface defined by said shear screen.
 24. An incinerator as defined in claim 1, further comprising ignition-burner means arranged to project a flame in the direction of the waste material in said first combustion chamber to thereby ignite the waste material.
 25. An incinerator as defined in claim 1, wherein said particle separating means comprises a plurality of parallel elongate transversely extending deflectors, the spaces between adjacent deflectors being substantially uniform and equal to approximately twice the dimensions of the largest particles.
 26. An incinerator as defined in claim 17, wherein said open top and bottom ends have dimensions smaller than the transverse dimensions of said second chamber, whereby confining surfaces are provided at said top and bottom ends for confining said reverberant flame within said second chamber.
 27. An incinerator as defined in claim 1, wherein said spaces provided in said separating means are substantially greater than average-sized particles which rise from said first to said second chambers.
 28. An incinerator as defined in claim 6, wherein said after-burner means is positioned exteriorly of said second chamber and is arranged to project a reverberant flame into said chamber, whereby the temperatures within said second chamber can be raised to a desired high level without damaging said after-burner means.
 29. An incinerator as defined in claim 1, further comprising support means in the form of a grate arranged in the lower region of said first chamber for supporting the waste material; receptacle means in the form of an ash pan arranged below said grate for receiving partially burned refuse and also ash generated by the burning of the waste material and for receiving wet waste and drippings thereof; and further ignition burner means arranged to project a flame in the direction of the waste material on said grate to ignite the same and which flame further sweeps across said receptacle means to reduce the waste material which drops thereinto.
 30. An incinerator as defined in claim 29, wherein said first chamber has a bottom wall positioned below said receptacle means, said air inlet means comprising air inlet openings in said bottom wall, whereby air which passes through said air inlet openings comes into direct contact with said receptacle means to cool the same and maintain the temperature of said receptacle means below the melting point of the latter.
 31. An incinerator as defined in claim 29, wherein said grate is inclined downwardly in the direction away from said further ignition burner means, with the highest point of said grate being above and further ignition burner means, whereby the flame of said further ignition burner means flame sweeps across substantially the entire under surface of said grate and is downwardly directed into said receptacle means by the converging action of said inclined grate. 